Disk drives are information storage devices that use thin film magnetic media to store data. Referring to FIGS. 1a and 1b, a typical disk drive in prior art has a drive arm 104 with a slider 203 mounted thereon and a magnetic disk 101. The disk 101 is mounted on a spindle motor 102 which causes the disk 101 to spin and a voice-coil motor (VCM) (not shown) is provided for controlling the motion of the drive arm 104 with the slider 203 and thus controlling the slider 203 to move from track to track across the surface of the disk 101 to read data from or write data to the disk 101.
However, Because of the inherent tolerance (dynamic play) resulting from VCM that exists in the placement of the slider 203, the slider 203 can not attain a position fine adjustment.
To solve the above-mentioned problem, piezoelectric (PZT) micro-actuators are now utilized to modify the placement of the slider. That is, the PZT micro-actuator corrects the placement of the slider on a much smaller scale to compensate for the tolerance of VCM and the drive arm 104. It not only enables a smaller recording track width, but also increases the ‘tracks per inch’ (TPI) value and the surface recording density of the disk drive.
Referring to FIGS. 1c, 1d, a traditional PZT micro-actuator 205 has a ceramic U-shaped frame 297. The U-shaped frame 297 comprises two ceramic beams 207 with two PZT pieces (not shown) on each side thereof. The PZT micro-actuator 205 is physically coupled to a suspension 213, and there are three electrical connection balls 209 (gold ball bonding or solder bump bonding, GBB or SBB) to couple the micro-actuator 205 to the suspension traces 210 in one side of the ceramic beam 207. In addition, there are four balls 208 (GBB or SBB) to couple the slider 203 to the suspension 213 for electrical connection. FIG. 2 shows a detailed process of inserting the slider 203 into the micro-actuator 205. The slider 203 is bonded with the two ceramic beams 207 at two points 206 by epoxy dots 212 so as to make the motion of the slider 203 independent of the drive arm 104 (See FIG. 1a).
When power supply is applied through the suspension traces 210, the PZT micro-actuator 205 can expand or contract to cause the U-shaped frame 297 deform and then make the slider 203 rotate along a radial direction on the disk 101. Thus a position fine adjustment can be attained.
However, a head gimbal assembly (HGA) 277 (see FIG. 1c) with the micro-actuator 205 is very difficult to manufacture. First, inserting and bonding the slider 203 to the micro-actuator 205 is difficult. Secondly, the epoxy dot 212 is very difficult to control, if the length of the epoxy dot 212 is too long, it will affect the work performance of the micro-actuator 205, for example, the displacement is not enough; if the length of the epoxy dot 212 is too short, the bonding strength will not be enough and then the shock performance is poor. In addition, the height of the epoxy dot 212 is also difficult to control, if the epoxy dot 212 is too high, the epoxy dot 212 will stay on the front or back side of the slider 203. The epoxy dot 212 staying on the front side of the slider 203 will influence the slider 203 flying on the disk 101 and even damage the slider 203 or the disk 101; The epoxy dot 212 staying on the back side of the slider 203 will influence the GBB process of the slider 203.
Additionally, the micro-actuator 105 has an additional mass which not only influence the static performance, but also influence the dynamic performance of the suspension 213, such as the resonance performance, so as to reduce resonance frequency and increase the gain of the suspension 213.
Also, because the U-shaped frame 297 of the micro-actuator 205 is very brittle, it has a poor shock performance. In addition, it is also a big problem that there is no effective method to identify potential micro cracks of the U-shaped frame 297. Furthermore, due to the variations of voltage applied to the PZT micro-actuator, the back and forth bending of the brittle micro-actuator 205 will generate particles and influence the work performance of the micro-actuator 205.
In the manufacturing process of HGA 277, since the HGA 277 has a complex configuration, the slider 203 must tilt during the bonding of the slider 203 to the U-shaped frame 297, and the U-shaped frame 297 must tilt during the bonding of the U-shaped frame 297 with the slider 203 to the suspension 213. Both will influence the static attitude of the HGA 277 and accordingly increase the difficulty of manufacturing the HGA 277.
It is well known that polishing is a more effective and widely used cleaning method for the micro contamination in the air bearing surface (ABS) of the slider. However, this cleaning method cannot be used in the above-mentioned HGA 277 because it is easy to damage the U-shaped frame 297 of the micro-actuator 205.
Finally, since the slider 203 is supported by the ceramic U-shaped frame 297, it is difficult to ground the slider 203 and suspension to get an electro static discharge (ESD) protection. Also, it is a waste of energy that a bigger drive voltage (40V, AC p—p) is required for operate the PZT micro-actuator 205.
Hence it is desired to provide a micro-actuator, head gimbal assembly and manufacturing method thereof which can overcome the foregoing drawbacks of the prior art.